On Mon, 2015-03-23 at 07:04 +0100, Arnd Bergmann wrote: > > My guess is that the ARM code so far has been concerned mainly with > getting things to work in the first place, but scalability problems > will only be seen when there are faster CPU cores become available. In any case, I think this is mostly a non-issue. The complexity of the ARM code is in various areas related to making shit work (handling coherent allocations mostly) but only remotely related to the actual iommu DMA space allocator (iova in ARM as far as I understand the code) which is pretty standard. The work Sowmini is doing is about specifically the allocator. Making our (powerpc) allocator generic since it has some nice scalability features. In fact, what Aik and I have been pushing and Sowmini is close to achieving is to mostly disconnect that allocator from the rest of the iommu management (the caller). So in the end, the allocator itself should be splitable into something separate that resides in lib/ or similar, which ARM can chose to use as well. Sowmini: it might be worthwhile creating a separate data structure iommu_virt_zone or something like that which is what the allocator works on exclusively, which we would just embed into sparc and powerpc. The only remaining problem I see is your "reset" op, but I think we should be able to sort it out once we understand what it's there for :-) Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
